Has Anyone Ever Seen a Bad Flywheel Cause No Spark?

[drf255]

I'm working on an MS280. The darn thing has no spark. I figured a bad coil, but much to my surprise, if I swapped a different flywheel in, the saw had spark.

The flywheel has a broken fin that did some damage to the flywheel. The magnets got ground down a bit.

The stock flywheel has two magnets covers with a plastic membrane and a plastic divider between the two. The damaged flywheel is missing this membrane and divider.

I'd never imagine some damage to the magnets would cause no spark. They're both still fully magnetic. I gapped the coil appropriately with no dice.

I guess with these newer saws and their computer chips, anything is possible.

 

[Rookie1]

Ive never seen that happen. Maybe the plastic piece has something to do with the magneto. I never seen an old flywheel not give juice to a points ignition. I like points. Old Skool baby!

 

[tomdcoker]

I sold an 029 flywheel to a man about a month ago to replace a damaged one. He came back about three days later with no fire, replaced the flywheel with another one that I had and he was back in business. That was a first for me. Tom

 

[drf255]

My issue was the flywheel. Looked ok except for the slightly ground down magnets. Finally found a replacement and git spark.

 

[AVB]

Wonder if the magnet polarity was wrong. I know on some old Briggs engines that can be the case when swapping from point coils to electronic coils.

 

[old-cat]

A customer brought an 038 magnum STIHL that would not run. I tried everything. Nothing was messed up. Finally I used some fine sandpaper on the flywheel magnets and it fired right up!

 

[Guido Salvage]

Is it a gap issue? If the magnets are "ground down" there may be too much of an air gap.

 

[drf255]

Is it a gap issue? If the magnets are "ground down" there may be too much of an air gap.

No. I set the gap. Tried it all.

The magnets are covered with a yellow film unmolested. Polarity the same. The bad flywheel had the film rubbed off.

All I can say is $50 more and it's running. This model is low production and relatively new. A really hard part to find used.

 

[jl4c]

A customer brought an 038 magnum STIHL that would not run. I tried everything. Nothing was messed up. Finally I used some fine sandpaper on the flywheel magnets and it fired right up!

What prompted you to think this might be a solution? Not arguing with your results, just curious.

 

[old-cat]

What prompted you to think this might be a solution? Not arguing with your results, just curious.

I didn't think there was any problem there. It just didn't look clean and bare. AND I was getting frustrated and desperate.

 

[jl4c]

I didn't think there was any problem there. It just didn't look clean and bare. AND I was getting frustrated and desperate.

The correct combination of frustration, desperation, perspiration and inspiration has certainly solved more than one such problem.

 

[wigglesworth]

I had a 262xp that had a bad flywheel back in the day. No spark, no matter what u did. Swapped coils, wires, plug...no dice. FW got it sparking again.

 

[drf255]

WTF is the cause though? Magnets still magnetic, gap set correctly. It's strange.

 

[pioneerguy600]

Check the poles of the magnets, see if they are different, one should be North the other South. Sometimes a magnet will reverse polarity if struck/hit hard.

 

[drf255]

That has to be it.

 

[tomdcoker]

Check the poles of the magnets, see if they are different, one should be North the other South. Sometimes a magnet will reverse polarity if struck/hit hard.

I do not know if I have heard this or dreamed it, but I thought that a hard lick ( when removing a flywheel) could possibly cause the magnets to quit working. Probably by reversing polarity. Tom

 

[pioneerguy600]

I do not know if I have heard this or dreamed it, but I thought that a hard lick ( when removing a flywheel) could possibly cause the magnets to quit working. Probably by reversing polarity. Tom

That could be possible Tom, I know plenty of flywheels get removed that way and still work afterwards but anything is possible with mechanicals. Only one I ever encountered was back in 1986 when my dad`s Sachs Dolmar 116`s module came loose and struck the flywheel rather badly. It gouged both the flywheel and the laminated coil/module frame. It lost spark and we put a new module in thinking it was damaged too badly , that did not fix the spark issue. I bought a new flywheel and that got it going, being the inquisitive fellow I am I then checked over the flywheel carefully. It was not badly damaged and not broken but I have a small pole magnet I keep in the tool box and low and behold both of the magnets in the flywheel were now South poles, it had to be from the laminate striking the flywheel. When I tried the old damaged module it would still make spark but would not run a saw, possibly firing at the wrong time, timing issue.

 

[Cantdog]

Hmmmmm.....this gives pause for thought.....I currently have two saws (clients saws) that have both been plagued with spark then no spark problems.....have swapped out coils several times on one.....run for a bit then stop...no spark. The other I have replace the entire ign, points, points plate, condenser, coil...same thing start and run fine then ...not....no spark. Flywheels look fine...but....the only thing not replaced...worth a shot I guess... have spares for both brands.....